Sarah Shourd (pictured in 2010 following her release) has described how she spent her days in solitary confinement 'full of rage'

A woman who was locked in solitary confinement for more than a year after accidentally crossing into Iran has described how she spent her days pacing her cell and 'full of rage'.

Sarah Shourd was one of three American hikers who were imprisoned after the holiday they took to Kurdistan in 2009 quickly turned into a nightmare when a guide led them astray.

Ms Shourd spent 410 days in solitary confinement, while her travelling companions Shane Bauer and Josh Fattal spent more than two years in prison.

She has now described the effect her time in solitary confinement had on her during a discussion on HuffPost Live about the findings of a PBS Frontline documentary called Solitary Nation

Ms Shourd said: 'In the beginning, it reduces you to an almost animal-like state.

'I spent all my days pacing my cell, punching the air, just full of rage. And then I would fall into deep depressions.'

She described how she would crouch by her door in an attempt to hear a human sound, such as a cough or a footstep, so she could be reminded she was 'in the land of the living.'

She also described how at times she lost her sanity and beat up the walls of her cell.

Last month it was reported Ms Shourd, Mr Bauer and Mr Fattal were telling their side of the story in the new book A Sliver Of Light.

Shane Bauer, Sarah Shourd and Josh Fattal speak at an event in February 2012. Mr Bauer and Ms Shourd were married in May 2012

Ms Shourd became severely depressed during her imprisonment, but there were a few periods of unexpected joy - including the time her boyfriend Mr Bauer proposed to her using strings he pulled from a towel fastened with a staple.